def perm_sym

bend-mathlib@0.8.1.0 · perm.bend:299

import Base
import bendlib-kernel-list@1.0.0.0/list.bend as K

299# Permutation is symmetric.
300def perm_sym(-A: Data, +xs: List<&2, A>, -ys: List<&2, A>, h: K.perm(A, xs, ys)) -> K.perm(A, ys, xs):
301  (s, e) = h
302  +s = s
303  (internal_invert(s), internal_sym_eq(A, s, xs, ys, e))